Question: Sixty percent of a plane's passengers are women and ten percent of those women are in first class. What is the number of women in first class if the plane is carrying 200 passengers?
Sixty percent of the plane's 200 passengers is $200\cdot \frac{60}{100} = 120$ passengers. Ten percent of these women are in first class; this is $120\cdot \frac{10}{100} = \boxed{12}$.